1. Technical Field
The present invention relates to a method for installing a measuring tape of an angle measuring device, and to an apparatus for performing the method.
The present invention further relates to a structural unit including a measuring tape and an apparatus for installing this measuring tape in accordance with the present invention.
2. Background Information
In angle measuring devices, increasingly there is a need to position a rotating object of relatively large diameter exactly. One example of such an application is large round tables in processing machine, but also telescopes. To enable the most exact possible angular positioning of the round table or telescope, it is known to make a circumferential surface available on the object to be measured and to install a measuring tape with a measurement graduation along the circumference. One simple known way to do this installation is to clamp the measuring tape over the circumference. The measuring tape is firmly restrained on one end, and the remainder of the measuring tape is wrapped around the convex circumferential surface of the object to be measured. By static friction between the circumferential surface and the measuring tape, locally different tension ratios develop in the measuring tape over the circumference. The deviation in the measurement graduation applied to the measuring tape varies along the measuring tape in a manner equivalent to the locally varying tension, which in particular leads to short-period errors in the angle measurement.
In German Patent DE 197 51 019 C2, an installation method and an apparatus are known with which the same tensioning force is introduced at both ends of the measuring tape that attains a reduction in angle error. However, when compared to systems in which only one end of the measuring tape is firmly joined to its underlay, and in the installation operation a tensioning force is exerted on the second end, the tension ratios over the entire circumference, especially with large diameters, are as before still inadequate for precise angle measurements.